Responsiveness of the aging circadian clock to light

S. Benloucif*, K. Green, M. L'Hermite-Balériaux, S. Weintraub, L. F. Wolfe, P. C. Zee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

The present study assessed whether advances in sleep times and circadian phase in older adults might be due to decreased responsiveness of the aging circadian clock to light. Sixteen young (29.3 ± 5.6 years) and 14 older adults (67.1 ± 7.4 years) were exposed to 4 h of control dim (10 lux) or bright light (3500 lux) during the night. Phase shifts of the melatonin rhythm were assessed from the nights before and after the light exposure. Bright light delayed the melatonin midpoint in both young and older adults (p < 0.001). Phase delays for the older subjects were not significantly different from those of the young subjects for either the bright or dim light conditions. The magnitude of phase delays was correlated with both sleep offset and phase angle in the older, but not the younger subjects. The present results indicate that at light intensities commonly used in research as well as clinical practice older adults are able to phase delay to the same extent as younger subjects.

Original languageEnglish (US)
Pages (from-to)1870-1879
Number of pages10
JournalNeurobiology of Aging
Volume27
Issue number12
DOIs
StatePublished - Dec 2006

Funding

We thank the research subject volunteers for their participation in these studies, the administrators and staff of the General Clinical Research Center, and Dr. Nancy Johnson from the Memory Disorders Research Core for assistance with the Neuropsychological testing. Dr. Borko Jovanovich provided statistical consulting. This work was supported in part by a grant from the national Center on Clinical Research Resources (NCRR-0048), Public Health Service Grants R01 HL67604, P01 AG11412, and K01 AG00810 and an Alzheimer's Disease Core Center grant (AG13854) from the National Institute on Aging to Northwestern University.

Keywords

  • Advanced phase
  • Aging
  • Circadian
  • Light
  • Melatonin rhythm
  • Phase angle
  • Phase delay
  • Phase shift

ASJC Scopus subject areas

  • Clinical Neurology
  • Geriatrics and Gerontology
  • Aging
  • General Neuroscience
  • Developmental Biology

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